This paper discusses the reasons for keeping small ruminants and investigates the areas in which technological improvements are likely to have most impact in increasing the output from sheep and goat enterprises in hot climates. The most important areas in which biological manipulation can raise productivity lie in the areas of improved nutrition and increased survival of young animals. Nutritional studies of animals receiving diets of natural tropical grazing and browse may not reflect the rations actually consumed due to the ability of animals to select high quality forage from what is on offer. One suggestion is made as to how this selection can be exploited to increase the productivity of the herd as a whole. Improved health care offers the largest potential for increases in productivity by reducing the large mortality of young animals seen in many tropical production schemes. Much of this mortality has its roots in parasite infection. Anthelmatics have proved valuable for short term therapy hut the speed at which parasites become resistant to drugs indicates that selective breeding of animals with resistance to parasites is a more valuable long term solution.